Architectural structures, such as office buildings, retail stores, churches, governmental facilities, warehouses, hospitals, apartments, houses etc., built in earthquake-prone areas sometimes are constructed with a base isolation system. During an earthquake or other sudden ground motion, an architectural structure without a base isolation system may accelerate very quickly. This acceleration, combined with the weight of the architectural structure, can lead to substantial, and potentially damaging, inertial forces in the supporting members of the architectural structure.
Base isolations systems help protect against earthquake damage by reducing the amount of horizontal acceleration experienced by the architectural structure. In general, base isolation systems operate by converting kinetic energy associated with the shock of the earthquake into another form of energy, usually heat, which is then dissipated. The base isolation system, in effect, de-couples movement of the foundation from movement of the architectural structure. Though the architectural structure will still move during the earthquake, the architectural structure will accelerate at a slower rate than the foundation, because of the energy dissipated by the base isolation system. Accordingly, the architectural structure may experience less severe inertial forces as a result of the base isolation system.
Conventional base isolation systems tend to be very complex and/or require specialized installation techniques. Furthermore, base members of the architectural structure may require modification to accommodate a conventional base isolation system. Consequently, conventional base isolation systems tend to be costly and therefore limited to high value structures such as skyscrapers, hospitals, laboratories, bridges, elevated roadways, and the like. Lower value structures, such as residential buildings, usually are not installed with a base isolation system, because their lower value does not justify the expense and time of installing a base isolation system.
Another issue with conventional base isolation systems is that they usually incorporate a horizontal rolling element positioned between the foundation and the architectural structure. Therefore, they may be unable to provide the architectural structure with the vertical restraint needed to resist wind uplift forces and/or overturning forces due to lateral loading from wind or earthquakes. The lack of uplift restraint can render an architectural structure susceptible to damage from upward vertical forces, which have the potential to move the structure off its foundation.
The present disclosure sets forth seismic damping systems and methods embodying advantageous alternatives to existing seismic damping systems, and that may address one or more of the challenges or needs described herein.